package net.pingfang.util;

import sun.misc.BASE64Decoder;

import java.io.*;

/**
 * Base64 工具类
 */
public class Base64Util {
    private static final char last2byte = (char) Integer.parseInt("00000011", 2);
    private static final char last4byte = (char) Integer.parseInt("00001111", 2);
    private static final char last6byte = (char) Integer.parseInt("00111111", 2);
    private static final char lead6byte = (char) Integer.parseInt("11111100", 2);
    private static final char lead4byte = (char) Integer.parseInt("11110000", 2);
    private static final char lead2byte = (char) Integer.parseInt("11000000", 2);
    private static final char[] encodeTable = new char[]{'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'};

    public Base64Util() {
    }

    public static boolean str2File(String base64FileStr, String filePath) {

        // 数据为空
        if (base64FileStr == null) {
            return false;
        }
        //判断文件夹是否存在
        File file = new File(filePath);
        if (!file.exists()) {
            try {
                file.getParentFile().mkdirs();
                file.createNewFile();
            } catch (IOException e) {
            }
        }
        BASE64Decoder decoder = new BASE64Decoder();
        OutputStream out = null;
        try {
            // Base64解码,对字节数组字符串进行Base64解码并生成文件
            byte[] byt = decoder.decodeBuffer(base64FileStr);
            for (int i = 0, len = byt.length; i < len; ++i) {
                // 调整异常数据
                if (byt[i] < 0) {
                    byt[i] += 256;
                }
            }
            InputStream input = new ByteArrayInputStream(byt);
            // 生成指定格式的文件
            out = new FileOutputStream(filePath);
            byte[] buff = new byte[1024];
            int len;
            while ((len = input.read(buff)) != -1) {
                out.write(buff, 0, len);
            }
        } catch (IOException e) {
//            log.error("str2File error:{}", ExceptionUtil.getStackTrace(e));
        } finally {
            try {
                assert out != null;
                out.flush();
                out.close();
            } catch (Exception e) {
//                log.error("str2File error:{}", ExceptionUtil.getStackTrace(e));
            }
        }
        return true;
    }

    public static String encode(byte[] from) {
        StringBuilder to = new StringBuilder((int) ((double) from.length * 1.34D) + 3);
        int num = 0;
        char currentByte = 0;

        int i;
        for (i = 0; i < from.length; ++i) {
            for (num %= 8; num < 8; num += 6) {
                switch (num) {
                    case 0:
                        currentByte = (char) (from[i] & lead6byte);
                        currentByte = (char) (currentByte >>> 2);
                    case 1:
                    case 3:
                    case 5:
                    default:
                        break;
                    case 2:
                        currentByte = (char) (from[i] & last6byte);
                        break;
                    case 4:
                        currentByte = (char) (from[i] & last4byte);
                        currentByte = (char) (currentByte << 2);
                        if (i + 1 < from.length) {
                            currentByte = (char) (currentByte | (from[i + 1] & lead2byte) >>> 6);
                        }
                        break;
                    case 6:
                        currentByte = (char) (from[i] & last2byte);
                        currentByte = (char) (currentByte << 4);
                        if (i + 1 < from.length) {
                            currentByte = (char) (currentByte | (from[i + 1] & lead4byte) >>> 4);
                        }
                }

                to.append(encodeTable[currentByte]);
            }
        }

        if (to.length() % 4 != 0) {
            for (i = 4 - to.length() % 4; i > 0; --i) {
                to.append("=");
            }
        }

        return to.toString();
    }
}
